As many noticed today, PTCWall reversed some advertisement, they explain as follow as can be seen on their news page:
Fraudulent/exploiting ads reversals
There has been some fraud/exploiting that took place, and we are adjusting for it. If your account is Negative or has fallen that means you were likely paid for clicks on the fraudulent ads. We are also taking the money out of the user's accounts to you don't lose anymore by paying them.
---We have fixed the issue so that they can't exploit the system like this anymore.
In most cases, we would not reverse them, but in this case, we need to so the site can continue running. We understand you may be upset, and your users may be upset, but it was a choice of cut this site from our list of sites or reverse some of the clicks on the fraudulent ads that happened recently and fix the exploit to keep the site open and running.
Please be aware we will not be paying out any cashouts for the next day or two tell we can finish this up and make sure everything is right. After that, we will start making payments again, please don't cash out ATM as we will need to manually delete and cash these out again to account for any change in balance and that will just make it take longer to clear all of this up.
We Hope that you will understand and not judge us too harshly.